Answer:
21
Step-by-step explanation:
Mean is the average of the objects
With five people, the mean is the average age of these people so what did you divide 5 into to get 39.
5 × 39 = 195
After a person enter the room, total 6 in the room with a mean of 36.
6 × 36 = 216
Now the age of the person who entered the room 216 - 195 = 21
